The Verge spoke to +Anil Sabharwal , head of Google Photos, about the new Photos app and the problems it solves for both Google and users. He told +The Verge how the new Photos solves a serious problem for Google: people didn't trust backing up their photos to Google+.

When [Google+] was introduced in 2012, Gundotra touted its unique privacy model, which asked users to group everyone they knew into "circles" of friends, family, co-workers, and so on. But few users could remember which people they had placed on which list, or bothered to update their lists as people moved in and out of their lives. Amid that confusion, Google found that people were reluctant to store their photos on its servers. "We needed to go back to the first principles," Sabharwal says. "We need to go back and start over."

In the wake of Gundotra’s departure, the Photos team began to rethink its approach. If they were going to ask people to store all of their pictures with Google, they would have to build a new foundation of trust. That meant "graduating" the service from Google+, and building a new home for it inside stand-alone apps and at photos.google.com. And it meant building a service that did as much to help you enjoy your old photos as it did to store them. The hope is that the fresh start will give people more confidence that their photos will be safe, and private, with Google.